Belly Armor, based in Singapore and New York, makes blankets and T-shirts for expectant mothers from a conductive textile made of fibers and metal. This creates a barrier much like a Faraday cage, a metal enclosure that protects those inside it from radiation.The idea is to neutralize environmental radiation before it reaches the fetus.

Belly Armor is available online and in stores in Asia, and will appear next month in some maternity boutiques in the United States.

The cases are currently available for BlackBerry and iPhone models. Dr. Alfred Y. Wong, Pong’s founder and a professor of physics at the University of California, Los Angeles, who invented the technology, said he planned to make them for more phones in the future.

“The level of exposure that people have today has grown exponentially over the past ten years as cellphones, BlackBerrys, iPods, everything has proliferated,” Mr. Lam said. “And studying the long-term impact of being around those has only started to happen.”

But whether exposure to electromagnetic radiation at the level released by wireless devices is harmful is open to debate.

There is enough public concern about the issue that legislators in California and Maine have called for warning labels on cellphones.

John Walls, vice president of public affairs for CTIA-The Wireless Association, a wireless communication trade group, said that while products to reduce the amount of radiation from phones could theoretically work, they were unnecessary.

“Science has not indicated there is a problem,” Mr. Walls said. “Phones are already emitting radiation below acceptable levels as per the F.C.C. regulations.”

While Dr. Wong admits that no study conclusively demonstrates risk, he still advocates caution. He said radiation from a cellphone was “the same as a microwave oven,” which works by “basically heating up the water in food.”

“Our brain and the whole body is 70 percent water, so it doesn’t take long to make that connection,” Dr. Wong said.

What's Next

About

Gadgetwise is a blog about everything related to buying and using tech products. From figuring out which gadget to buy and how to get the best deal on it to configuring it once it’s out of the box, Gadgetwise offers a mix of information, analysis and opinion to help you get the most out of your personal tech.